Method and apparatus for beating pulp



m 2:2 "Hm-E 47 Ja n. 26, 1932, A. D. LITTLE 1,342,753

METHbD AND APPARATUS FOR HEATING PULP Filed NOV-7, 1929 Patented Jan. 26, 1932 UNITED STATES ARTHUR DEHAN LITTLE, F BROOKLINE, MASSACHUSETTS, ASSIGNOR, BY MESNE ALS' PATENT OFFICE SIGNMENTS, T0 RUBBER SURFACERS, INC., OF WILMINGTON, DELAWARE, COR- PORATION or DELAWARE METHONAND APPARATUS FORBEATING P 'ULP Application filed November This invention relates to an improved method and apparatus for treating fibrous material and more particularly for beating pulp or paper stock whereby the felting. properties of the fibers are improved and, in the case of vegetable fibers, the fiber substance is also hydrated while minimizing the shortening of the fiber length which results from the cutting or breaking of, the fibers when beaten by the methods now com monly used. The new method and apparatus also reduces the time usually required for the beating treatment and produces a stock which improves the tearing,.tensile, bursting and folding strength -of'the pa er made from it.

It has heretofore been t e practice in the paper and allied industries to subject the stock or pulp to the action of a beating machine or heater of which a common type is the well known Hollander. The usual beating machine consists of an oblong trough having semi-circular ends with a partition running along the center and terminating short of the ends so as to form a continuous channel around the trough. At one side of the oval trough thus formed is situated the beating roll on a horizontal axis extending across the channel. The heating roll is commonly furnished with a number of steel or bronze blades or knives extending lengthwise of the axis of the roll.' In the bed of the trough under the beating roll is the bed-plate shaped to conform in general to the curvature of the roll and equipped with steelor bronze blades similar to those of the roil. a clearance between the blades of the roll and those of the bed-plate and the roll is usually provided with means for adjusting this clearance to the desired extent.

By reason of the inherent hardness and rigidity of the steel or. bronze blades or knives commonly used in the beater the blades have a shearing and cutting effect on the pulp so that the fibers are to a large extent cut ofi with the result that the fibers so out are not only shortened but are left with more or less clean cut ends instead of ends in a frayed ortorn condition which is desirable to give the pulp good felting properties. By shearing I mean the application to the pulp of There is r 7, 1929. Serial No. 405,313.

the beating forces in opposite directions in parallel planes which are offset one from the other and are relatively fixed, ,at least within the limits of compression of the yielding beater elements presently to be described. Shearing may or may not be accompanied by cutting. With the usual rigid metallic blades heretofore used in beaters the shearing is inevitably accompanied by the cutting of fibers. With the present invention this cutting action is largely avoided and the fiber ting edges or surfaces and which exert onthe pul" a shearing efi'ect without cutting, in place 0 the hard, rigid, metallic blades heretofore used. Preferably these blades are of rubber (by which I mean to include rubber covered blades), the rubber used being of about the consistency of that used in rubber automobile tires. The word rubber as used throughout the specification and claims 'includes not only rubber and rubber compositions in a strict sense but also rubber sub stitutes and equivalent compositions having the proper rubber-like consistency and physical eharacteristics for making yielding, resilient blades suitable for performing the method of the present invention. These cushion-like blades of rubber or equivalent substance not only yield as a whole to the pulp, but are also capable of yielding locally to bundles of fiber or'bunches, thereby further minimizing the danger of injury to the .fibers during the heating process. By the rotation of the roll, the pulp is fed forward by the blades on the roll separated by channels and, having passed over the bed-plate and under the roll, is lifted over the usual backfall, which is a raised portion of the bed of the trough, whereby the level of the material in the heater is so raised beyond the backfall as to cause the pulp to circulate around the trough and thereby to pass successively-many times between the revolving beater roll and the bed plate. The fiber bundles and fibers are thus subjected sub stantially without cutting them to a shearing action characterized by rubbing, crushing, flattening, pulling and bruising by the resilient blades, so that the fiber bundles are separated into their individual fibers and the fibers are hydrated and frayed, as contrasted with the usual cutting action, the degree of hydration depending largely upon the seheretofore commonly used. The squeezing,

crushing and rubbing action between the sur- "faces of the relatively yielding blades tends to flatten out theifibers and to split them into fibrillae and to gelatinize or hydrate the fibers in a manner which develops their felting and inherent strength-giving properties without objectionable shortening of the fibers. The average length of the beaten pulp fiber is greater than in similar pulp subjected to the cutting action of the ordinary heater and the pulp is relatively free from out fiber and blunt ends found in the pulpbeaten in an ordinary, beater. Paper can be produced from the pulp resulting from the beating process of the present invention having higher tensile strength and bursting strength, higher tearing strength and higher folding strength than with the same pulp beaten bv usual methods. Moreover, the pulp itself is a free pulp from which the water readily drains away faster than with pulp treated to the same extent in an ordinary beater. Freeness, as that term is used in paper making, denotes the" rate at which water drains away from the pulp on the wire of the paper making machine. The principal factors affecting freeness are the hydration of the individual fibers and the average length of the fibers. Hydration tends to make a pulp slow (that is, less free) but that is more than offset by the fiber length resulting fromthe method 0 the present invention. A free pulp is def sirable in that it permits increasing the speed of the paper making process, and hence reduces the cost, for the reason that the water will drain away faster from the pulp on the wire and the presses will express more water than from a less free pulp and hence the volume of the water which must subsequently be removed by the dryers is reduced. By reason of the increased average length of the fibers produced by the new method of the present invention the freeness of the pulp is improved notwithstanding the fibers are adequately hydrated.

In the accompanying drawings which illustrate the new ap aratus suitable for practicing the new met 0d: Fig. 1 is a plan view;

Fig. 3 is a detail view on an enlarged scale in section illustrating one construction of the yielding, resilient blades on the bed-plate and beater roll; and

Figs. 4, 5, 6 and 7 illustrate details, partly in section and partly in end elevation, of alternative constructions of the bladeson the beater roll, it being understood that similar constructions are applicable as well to the bed-plate if desired.

The invention may be practiced in a Hollander or beating machine of usual type comprising a trough 10 having rounded ends and a central partition 11 terminating short of the ends to provide a continuous channel around which the stockcirculates. The ulp is circulated around the'trough in a c ockwise direction, as indicated by the arrow in Fig. 1, passing between the beater roll 12 and the bed-plate 13, and is lifted-over the back-- fall 14 by the roll 12 which rotates in the direction of the arrow in Fig. 2. The beater roll 12 is mounted on a shaft 15 which extends across the trough and is journalled in bearings which are vertically adjustable to Fig. 2 is a longitudinal section on line 22 varythe clearance between the beater roll and a the bed-plate. The beater roll is driven by a pulley 16 on shaft 15. The parts thus far described may be of common andwell known constructions and no further detailed description will be necessary.

The. present-invention has to do with the treatment of the fibrous material by a rubbing, crushing and shearing action substantially devoid of cutting action, and with the yielding, resilient or cushion-like beating elements for performing that function, as contrasted with the cutting action of the metallic blades used in ordinary beaters. As illustrated in Figs. 2 and 3 the blades 17 on the beater roll are made of solid rubber integral with the backing or mat 18; The backing 18 with its blades 17 may be made in a single sheet of a width equal to the length of the roll so that a length of sheet equal to'the circumference of the roll may be cut to measure and cementedor vulcanized to the body or'core of the roll; or it may be made in sections and cementedto the roll in that manner.

.The bed-plate 13 may similarly be made of solid rubber with integrally formed blades .19 of rubber.

Although it is preferable that both the beater roll and the bed-plate be equipped with. rubber or equivalent yielding, resilient blades, as just described,-the advantages of the invention may be realized to a measurable extent even if one or the other of such beater members be equipped with the usual metallic blades provided the other is equipped with the yielding, resilient blades. And treatment by such yielding, beating elements or blades onone side of the pulp only is included in the invention and intended to be secured by the claims excepting those claims which are expressly limited to suchtreatment' on both sides of the pulp.

Instead of making the rubber blades integral with the backing or the bed-plate, as the case may be, they may consist of rubber strips as illustrated in Fig. 4 made with lengthwise grooves mounted on T bars 21, the stems of the T bar being fitted into the grooves of the rubberjstrips. The rubber strips may be vulcanized or cemented on to the T bars and these in turn fastened to the core of the roll by bolts or the like. Another modification is shown in Fig. 5 which illustrates blades 22 consisting of solid rubber strips made of rectangular cross sec-- tion and held by compression or by cementing or both between the flanges of the channel bars 23 which are fastened to the core of the beater roll. I

The modification illustrated in Fig. 6 is similar to that of Fig. 5 .but instead of channel bars with right angle flanges it has channel bars 24 whose flanges are laterally inclined or flared for pinching and compressing the sides of the rubber strips, between the flanges of adjacent channel bars, as illustrated, thereby enhancing their gripping and holding effect.

The further modification shown in Fig. 7

comprises metal bars secured in grooves in the core of the roll in the manner in which it is customary-to attach themetal blades of usual beater rolls. The rubber strips 22 are clamped to the bars 25 on their forward side with reference to the direction of rotation of the roll by means of metal bars 26 fastened to the bars 25 by bolts passing through the rubber.

In all the various forms suggested yielding, resilient, cushion-like blades are provided which exert a rubbing, crushing and shearing action on the pulp substantially without cutting action. The blades are rather blunt in form and their spacing, which forms the channels between them, may be somewhat varied for example, in Figs. 3 and 4 the spaces or channels between blades are shown' as approximately. equal to the thickness of the blades, while in Fig. 7 the blades are spaced at greater intervals.

When the pulp is drawn between the beater roll and the bed-plate by the revolution of the roll and subjected to the beating action of the resilient, yielding blades, certain forms of which have been described by way of illustration, the efiect is to rub, crush, abraid, pull and shear the pulp without substantial cutting, so as to separate the bundles of fibers into individual fibers and to fray out the ends of the individual fibers, hydrate them and prepare them for effective felting, while at the same time substantially preserving the desired length and strength of the fibers and avoiding such injury to'the fibers as takes place in ordinary beating operations.

While the present invention is of particular value for the beating of chemical wood fiber, it includes in its broader' aspects the beating of other materials which require similar treatment. I am aware that it has been proposed to treat fibrous material by subjecting it to the action of a ball mill or rod mill containing a multiplicity of independent, loose, grinding elements consisting of rubber covered lead balls or rubber covered steel rods with which the fibrous material is tumbled. The action on the fibrous material of such loose balls or rods by their weight and impact is to be sharply distinguished from the non-cutting shearing action of the present invention, and I make no claim to the method or construction of such ball mill or rod mill. I claim:

1 1. A beating machine for fibrous material comprising a bed plate and a beater roll, one at least of which is provided with yielding, resilient, beating elements adapted to beat the fibrous material passing between the bed plate and roll by a rubbing, crushing and shearing action without substantial cutting action.

2. A beating machine for fibrous material comprising a bed plate and a beater roll, both of which are provided with yielding, resilient, heating elements adapted to beat the fibrous material passing between the bed plate and roll by a rubbing, crushing and shearing action without substantial cutting action.

3. A beating machine comprising a bed plate and a beater roll, one at least of which is provided with yielding, resilient blades extending across the path of material passing between the bed plate and beater roll.

4. A beating machine comprising a bed plate and a beater roll, one at least of which is provided with rubber heating elements.

5. A beating machine comprising a bed plate and a heater roll, one at least of which is provided with rubber beating blades extending across the path of material passing between the bed plate'and roll.

'6. A beating machine comprising a bed plate and a beater roll, both of which are providedwith rubber beating blades extendplate and a'beater roll, both of which are provided with blades of yielding, resilient material.

'9. The method of beating fibrous materials in a beating machine of thekind having a bed plate and beater roll which comprises passing the material between the bed plate and heater roll, and subjecting the material to the act-ion of yielding, beating members on both sides of the passing material.

10. The method of beating fibrous materials in a beating machine of the kind having a bed plate and beater roll which comprises passing the material between the bed plate and beater roll, and subjecting the material to the action otyielding, resilient blades on both sides of the passing material.

11. The method of beating fibrous materials in a beating machine of the kind having :1 bed plate and beater roll which comprises passing the material between the bed plate and beater roll, and subjecting the material to the action of rubber blades on both sides of the passing material.

- y In testimony whergeof I aflix my signature.

ARTHUR DEHAN LITTLE. 

